Nitrated fabric and method of making same



July 1, 1930. I A. LONDON ET AL 1,769,702

NITRATED FABRIC AND METHOD OF MAKING SAME Filed Aug. 7, 1929 l NVENTOR 3 BY a TI'ORNEY Patented July 1, 1930 v UNITED STA TES PATENT OFFICE AARON- oNnoN AND .rosnrn narrow, or BROOKLYN, NEW YORK I NIQRATED FABRIC ,AND METHODOF MAKING SAME Application filed August 7,

10 which is readily soluble in solutions such as caustic soda which do not affect the lace threads, and which is of such physical characteristics as to be practically adapted to be workedupon by the 1ace machine.

Other objects of this invention will in part be obvious and in part be hereinafter pointed out.

In accordance with our invention, a cheap cotton fabric such as ordinary cheese cloth, or any other cheap cellulose fiber; such as flax,

'jute, ramie, or the like, is treated chemically to render the cellulose fibers soluble in caustic soda. While, generally speaking, the treatment of cellulose with a solution of nitric and 2 sulphuric acid to render the same soluble in caustic soda is a well known art, briefly described, the dominant feature of our invention resides in the combination and apportionment of the ingredients of the nitrating bath and themethod of treatment hereinafter described, whereby is provided a backing of the character referred to, possessing to a high degree the necessary physical characteristics to adapt itfor the purposes above mentioned, with a high degree of economy in time, labor and materials, thus affording a very inexpensive product.

We have found that in order that the backing shall be sufficiently strong for spanning or stretching in frames for the lace machine and yet be sufiiciently soft,'a nd soluble in the caustic soda, a high percentage of nitric acid is best employed for the nitrating bath, a low percentage thereof resulting in too brittle a fabric which falls apart and-cannot be effectively stretched or spanned for the needle work. I

- More particularly, we have found that the nitratin bath should comprise an aqueous so- 50 lution rom 50% to 80% nitric acid, and

1929. Serial N0; 384,211.

40% to 10% sulphuric acid, and further that best results are obtained when the nitration is carried out under a bath' and room temperature of from about 70 F. to 125 F. As an example, a solution which we have found to produce very good results comprises 70% nitric acid, 20% sulphuric acid and 10% water with the room and bath at about 100 F. With the nitrating solution having the ingredients in the proportions thereof above mentioned,'the nitrated fabric may be producedpreferably as follows, reference being had to the accompanying diagrammatic drawing:

The raw fabric is fed in a double layer from two feed rolls 10, whence it is drawn through rolls 11 into the nitrating tank 12, located preferably in a room or chamber 12, and passes out of the nitrating tank over a'guide roll 13 to a pair of squeeze rolls 14 which squeeze out any excess acid, the squeeze rolls being so arranged that such excess drops back i into the tank. From these squeeze rolls the dipped cloth is passed to and fro in the air by means of a number of guide rolls 15 over spaced glass rollers 16.. The guide rollers and the glass supports are so arranged and so spaced and the speed of the travel of the material such that the dipped fabric is exposed to the air in the chamber for from one to three minutes. In this way the acid of the nitrating bath is given suflicient time to act upon the cloth and effective nitration obtained without allowing the fabric to remain too long in the acid tank and with considerable economy in acid consumption. After being thus passed back and forth in the open air the cloth is drawn out of the chamber 12 between a number of water jets 17 for spraying the same to wash off any remaining excessof acid, and thence between squeeze rolls 18 for squeezing out the excess water. From these squeeze rolls the cloth passes over guide rolls 19" into a neutralizing tank 19 containing soda ash for neutralizing any free acid, and thence to a pair of squeeze rolls 20 for squeezing out any excess of soda ash, such squeeze rolls being likewise so arran ed that the excess of soda ash drops back into the neutralizing tank. From the neutralizing tank the cloth is passed over guide rolls 21' terial from the solution and exposing the into a fireproofing, dyeing and softening bath 21, comprising dye for giving the cloth any desired color, fireproofing material such as epsom salt to make the same fireproof, and a softener such as glycerine. The latter has been found to aid materially in preventing the needles of the lace machine from rusting when the cloth has been placed in the machine and allowed to remain therein for some time. From the last named bath the cloth again passes between squeeze rolls 22 for squeezing out the excess, of the bath solution, these squeeze rolls being likewise arranged so that such excess will drop back into the tank. From the last named squeeze rolls the cloth is passed in two separate layers onto drying frames.

lace unaffected, and is yet so cheap to produce as to considerably reduce the cost of production of the machine lace work.

'e have also found that by this process the fabric is produced with great economy of time and labor and materials.

It will thus be seen that there is provided a material and process in which the several objects of this invention are achieved, and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiment set forth, it is to be understood that all mattor-herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, we

. claim as new and desire to secure by Letters Patent:

1. The method of making a backing or ground of the character described consisting same to a temperatureof from ,to 125 F.

3. The method of making a backing or ground of the character described consisting in dipping a cellulose material in a solution containing from 50% to nitric acid, 40 to 10% sulphuric acid and having a temperature of from 70 to 125 F. then removing the material from the solution and exposing the same to a temperature of from 70 to 125 F. for from one to three minutes.

4. The method of making a backing or ground of the character described consisting in dipping a cellulose material in an aqueous solution containing from 50% to 80% nitric acid, 40% to 10% sulphuric acid, and having a temperature of from 70 to 125 F. then re-' moving the material from the solution and exposing it for from one to three minutes, and then washing off remaining excess of acid. 7

5 5. The method of making a backing or -solution containing from 50% to 80% nitric acid, 40% to 10% sulphuric acid, at a temperature of from 70 to 125 F. then removing the material from the solution and exposing the same to a temperature of from 7 0 to 125 F. for from one to three minutes, then washing off remaining excess of acid, then inserting the washed material in a neutralizing bath, and then removing said material from said bath and immersing the same in a bath containing fireproofing material.

7. The method of making a backing or ground of the character described consisting in dipping a cellulose material in an aqueous solution containingfrom 50% to 80% nitric acid, 40% to 10% sulphuric acid, and having a. temperature of from 70 to 125 F. then removing the material from the solution and exposing the same to a temperature of from 70 to 125 F.'for from one to three minutes, and then washing ofi' remaining excess of acid, then inserting the washed material in a neutralizing bath, and then removing said material from said bath andimmersing the same in a bath containing fireproofing material and a softener.

8. The method of making a backing or ground of the character described consisting in dipping a cellulose material into an aqueous solution containing from 50% to 80% nitric acid, 40% to 10% sulphuric acid, and having a temperature of from to 125 F. then removing the material from the solution and exposing the same to a. temperature of from 70 to 125 F. for from one to three minutes, then washing off remaining excess of acid, then inserting said washed material in a neutralizing bath, then removing said material from said bath and immersing the same in a bath containing a fireproofing material, a softener and a dye.

9. The method of making a backing or ground of the character described consisting in dipping a cellulose material in a solution containing from 50% to nitric acid, 40% to 10% sulphuric acid, and having a temperature of from 7 0 to 125 F. then removing the material from the solution and exposing the same to a temperature of from 70 to 125 F. for from one to three minutes, then Washing off any remaining excess of acid, then inserting said washed material in a neutralizing bath, and then removing said material from said bath and inserting the same ina bath containing a softener an 10. The method of making a backing or ground of the character described consisting in dipping into a solution comprising 70% nitric acid, 20% sulphuric acid and 10% water, a cellulose material at a temperature of 100 F.

11. The method of making a backing or ground of the character described consisting in dipping into a solution comprisin 70% nitric acid, 20% sulphuric acidan 10% water, a cellulose material at a temperature of 100 F. then removing said material from said bath and exposing the same to a temperature of 100 F.

12. The method of making material of the character described inserting the material containing cellulose fiber into a bath containing 50% to 80% nitric acid, 40% to 10% sulphuric acid, then removing said material) from said bath, squeezing the same to re move excess acid, then exposing said material to a temperature from 70 to 125 F. then washing said material with water, then squeezing said material to remove excess water, then immersing said material in a neutralizing bath, then squeezing said material, and then inserting said material into a bath containing a fireproofing material, a softener and a dye.

13. The method of making a backing or ground of the character described consisting in dipping a cotton fabric in an aqueous solution of nitric and sulphuric acid containing from 50% to 80% nitric acid,-40% to 10% sulphuric acid at a temperature of from 70 to 125 F.

14. The method of making a backing or ground of the character described consisting tu es.

r AARON LONDON.

JOSEPH DATLOW. 

